La primera fase incluyó la adición de un aula y luego otra, con el total de seis aulas de la escuela primaria.
 
1970
Una segunda fase de construcción añadió dos salones de kindergarten, con una entrada y un área de juego separadas.
 
1981
Una tercera fase, agregó tres aulas más para la escuela primaria, una sala de usos múltiples para música y juegos, salas para el personal y una nueva entrada y un patio para reemplazar la entrada previa al kínder y la cancha.
The Delft Montessori's individual classrooms have direct access to smaller terraces of their own, with garden plots and natural areas adjacent for projects and study activities.
Photo: R. Thomas Hille
To encourage interactive use, the Delft Montessori School library is contained within the open space of the hall. A freestanding reading table and book display provides additional opportunities for spontaneous activities.
Photo: R. Thomas Hille
An unusual feature of the Delft Montessori kindergarten hall is a recessed group sitting area in the center of the floor that deliberately obstructs the flow of circulation through the space.
Photo: R. Thomas Hille
Within a Delft Montessori classroom, the split-level L-shaped configuration establishes two distinct zones. The smaller subspace, located adjacent to the entrance and several steps lower than the main classroom, accommodates projects and other small-group activities.
Photo: R. Thomas Hille